2185
Inorg. Chem. 1981, 20, 2185-2188 attributable to the interference of the two chlorine atoms in cis positions. These adjacent C1 atoms not only provide strong steric interaction but also electrostatic repulsion. Acknowledgment. We are grateful to Dr. M. T. Wu of the Department of Chemistry, Chun Shan Institute of Science and Technology, for the help of data collection on a Nonius CAD-4F diffractometer. This work has been financially
supported in part by the National Science Council, Republic of China. Registry No. I, 70787-84-7. Supplementary Material Available: Tables of anisotropic thermal parameters of nonhydrogen atoms and structure factor amplitudes for I (6 pages). Ordering information is given on any current masthead page.
Contribution from the Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
Synthesis, Chemistry, and Low-Temperature Crystal and Molecular Structure of [y-(v5-Cyclopentadienyl)beryllio]octahydropentaborane, [p- (v5-C5H5)Be]B5H8 DONALD F. GAINES,* KRAIG M. COLESON, and JOSEPH C. CALABRESE
Received December 2, 1980 Reaction of ($-CSH,)BeC1 with KBsHs results in formation of the title compound, which forms crystals in the monoclinic space group P 2 , / c with u = 10.266 (8) A, b = 5.616 (4) A, c = 16.187 (7) A, /3 = 98.50 ( 5 ) O , V = 923.0 ( 5 ) A’, and Z = 4. The low-temperature X-ray structure was solved by direct methods, using anisotropic refinement of positional and temperature factors for nonhydrogen atoms and isotropic refinement for hydrogen atoms, which converged to R,= 0.0551 and Rz = 0.0831 for 1294 independent observed reflections. The structure of [p($-C5HS)Be]B5H8is like that of BsH9, but with a bridge hydrogen replaced by the ($-C5H5)Be moiety. Selected chemical properties of the title compound are described.
Introduction Beryllium, in the form of Be(BH4)2,may be inserted into a borane cluster by reaction with 1-ClB5H8to produce 2-berylla-2-(tetrahydroborato)hexaborane(1l),I BSHloBeBH4, which has a six-vertex pentagonal-pyramidal B,-Be cluster framework.* The mechanism of this reaction is complex, and Be(BH& presents some handling difficulties. Thus other synthetic routes to beryllaborane clusters are desirable. The successful insertion of boron, as (CH3)2BCl,into a bridging position in pentaborane(9) and subsequent rearrangement to a hexaborane(l0) derivative3 (eq 1) suggested that a similar LiBsH8 (CH3)*BC1 [p-(CH3)ZB]B5H8 2,3-(CH&%H8 (1) insertion might wcur with use of selected beryllium compounds. We present here the results of our initial investigations of such a beryllium-insertion reaction, in which ($-CSH,)BeCl was used as the insertion reagent. Results and Discussion The reaction of ($-C5HS)BeC1 with KBsH8 in a pentane slurry at ca. -40 OC produces good yields of [p-(v5-C5H5)Be]B,H8 according to eq 2. The product is a colorless solid
+
KBSHs
-
-
+ ($-C5H5)BeC1
-
KCl
+ [p-($-C5H5)Be]B5H8
(2) of low volatility that melts at ca. 38 OC. Characterization of the product was accomplished initially via mass and NMR spectroscopy, and the detailed structural parameters were obtained from a single-crystal X-ray study. The ambient IIB FT NMR spectrum of [p-(q5-CsH5)Be]B5H8is appropriate for a p-substituted BSH9derivative. It consists of three doublets of intensity 2:2: 1 at b -1 3.4 (J = 161 Hz), -21.8 ( J = 141 Hz), and -54.6 ( J = 170 Hz), respectively. With ‘H decoupled, “B(apex)-”B(base) coupling is observed in both sets of basal boron resonances. ( 1 ) Gaines, D. F.; Walrh, J. L. J . Chem. Soc., Chem. Commun. 1976,482; Inorg. Chem. 1978, 17, 1238. (2) Gaines, D. F.; Walsh, J. L.; Calabrese, J. C. Inorg. Chem. 1978, 17, 1242. (3) Gaines, D. F.; Iorns, T.V. J. Am. Chem. Soc. 1970, 92, 4571-4574.
0020-166918 111320-2185$01.25/0
Table I. Interatomic Distances (A) for [M-(~~-C,H,)B~]B,H, C(l j C ( 2 ) C(l)-C(5) C(ljH(6) C(2)-C(3) C(2)-H(7) C(5)-H(4) C(5)-H(10) C(4)-C(3) C(4)-H(9) C(3)-H(8) Be(l)-C(l) Be(l)-C(2) Be(l)-C(S) Be(l)-C(4) Be(l)-C(3) Be(1)-B(2) Be(1)-B(3) B(2)-B(3)
1.391 (3) 1.397 (3) 0.931 (22) 1.398 (3) 0.929 (24) 1.401 (3) 1.045 (24) 1.396 (4) 0.980 (33) 0.899 (27) 1.886 (3) 1.894 (3) 1.892 (3) 1.877 (3) 1.884 (3) 2.045 (3) 2.055 (3) 1.726 (3)
B(2jB(5) B(2)-H(2) B(2)-H(5-2) B(l)-B(2) B(l)-B(3) B(l)-B(4) B(l)-B(5) B(l)-H(l) B(3)-B(4) B(3)-H(3) B(3)-H(3-4) B(4)-B(5) B(4)-H(4) B(4)-H(3-4) B(4)-H(4-5) B(5)-H(5) B(5)-H(4-5) B(5)-H(5-2)
1.812 (3) 1.102 (20) 1.263 (20) 1.696 (3) 1.705 (3) 1.675 (3) 1.663 (3) 0.980 (25) 1.821 (3) 1.041 (20) 1.268 (20) 1.799 (3) 1.039 (20) 1.251 (22) 1.242 (21) 1.065 (27) 1.293 (20) 1.310 (21)
the most interesting feature of the I1BNMR spectrum is the large upfield shift of the resonances associated with two of the basal borons, suggesting a higher concentration of electron density, while the other chemical shifts are not significantly different from those of B5Hg. It is interesting to note that the average of the chemical shifts for the two sets of basal boron resonances of [p-(~S-C,H5)Be]BsH8 is the same as that observed for BSH8- salts.3 The static structure, solubility in hydrocarbons, and volatility, however, confirm the covalency of the B-Be-B bonding. The 270-MHz ‘H FT N M R spectrum contains a sharp singlet at 6 5.4 (C,H,), quartets at 6 2.7, 1.8, and 1.1 (B,-H) for the terminal B-H’s, and broad singlets of intensity 1:2 at 6 -2.5 and -3.7, respectively, for the bridging hydrogens. The X-ray determined structure of [p-(~5-C5H5)Be]BsHl,, is shown in Figure 1. The internuclear distances and angles are given in Tables I and 11, respectively. Some interesting features appeared in the structural data which were not discernible from the NMR data. The shortening of the B(2)B(3) distance (Table I) suggests a higher concentration of electron density in this region in agreement with the assignment of the higher field resonance in the IlB NMR spectrum to the borons adjacent to beryllium. The tilt of H(4,5) under 0 1981 American Chemical Society
Gaines et al.
2186 Inorganic Chemistry, Vol. 20, No. 7, I981 Table 11. Intramolecular Angles (Deg) for [p-(q5-C,H,)Be]B5H8 89.1 (5) 108.7 (2) B(2)-B(5)-B(4) C(2bC(1)-CG) 136.3 (15) 68.7 (1) B(2)-B(5)-H(5) C(2)-C(l)-Be(l) 103.8 (9) 124.6 (13) B(2)-B(5)-H(4-5) C(2)-C(l)-H(6) 44.2 (9) 68.5 (1) B(2)-B(5)-H(2-5) C(S)-C(l)-Be 134.3 (15) 126.4 (13) B(4)-B(5)-H(5) C(5)-C(l)-H(6) 43.7 (9) 123.9 (13) B(4)-B(5)-H(4-5) Be( 1)-C( 1)-H(6) 107.7 (2) B(4)-B(5)-H( 2-5) 107.9 (8) C( 1)-C(2)-C(3) 106.5 (18) 68.1 (1) H(5)-B(5)-H(4-5) C(l)-C(2)-Be( 1) 104.9 (17) 132.3 (15) H(5)-B(5)-H(2-5) C(l)-C(2)-H(7) 128.3 (19) 67.9 (1) Be(l)-C(4)-H(9) C( 3)-C(2)-Be( 1) 108.1 (2) 119.6 (15) C(2)-C(3)-C(4) C(3)-C( 2)-H(7) 68.7 (1) 124.0 (16) C(2)-C(3)-Be(l) Be( 1)-C(2)-H(7) 126.1 (19) 107.3 (2) C(2)-C(3)-H(8) C( 1)-c(5)-c(4) 68.1 (1) 68.1 (1) C(4)-C(3)-Be(l) C( l)-C(S)-Be(l) 117.5 (14) C(4)-C(3)-H(8) 125.7 (19) C(l)-C(S)-H(lO) 125.8 (19) 67.6 (1) Be(l)-C(3)-H(8) C(4)-C(5)-Be( 1) 43.2 (1) 135.0 (13) C(l)-Be(l)-C(2) C(4)-C(5)-H( 10) 43.4 (1) 125.5 (14) C(l)-Be(l)-C(5) Be( 1)-C(5)-H( 10) 73.6 (1) 108.2 (2) C(l)-Be(l)-C(4) C(5 kC(4)-C(3) 73.4 (1) 68.7 (1) C(l)-Be(l)-C(3) C(5)-C(4)-Be( 1) 147.2 (2) 125.5 (17) C(l)-Be(l)-B(2) C(5)-C( 4)-H( 9) 124.7 (2) C(5)-C(4)-Be( 1) 68.5 (2) C(lhBe(lkB(3) 73.5 (1) 126.4 (17) C(2)-Be(l)-C(3) C(5)-C(4)-H(9) 73.7 (1) C(4)-Be( 1)-B(3) 132.3 (2) C(2)-Be(l)-C(4) 43.4 (1) C(3)-Be( 1)-B(2) 117.9 (2) C(2)-Be(l)-C(3) 122.4 (2) 161.6 (2) C(Z)-Be(l)-B(2) C(3)-Be( 1)-B(3) 151.9 (2) 49.8 (1) C(2)-Be(l)-B(3) B(2)-Be( 1)-B(3) 43.6 (1) B(l)-B(2)-B(3) 59.7 (1) C(5)-Be(l)-B(4) 73.7 (1) 56.5 (1) C(5)-Be(l)-C(3) B( 1)-B(2)-B(5) 164.0 (2) 124.7 (2) C(5)-Be(l)-B(2) B(l)-B(2)-Be( 1) 115.9 (1) 126.1 (11) C(5)-Be(l)-B(3) B(l)-B(2)-H(2) 43.6 (1) B( l)-B(2)-H(5-2) 102.1 (9) C(4)-Be(l)-C(3) 136.9 (2) 91.2 (1) C(4)-Be(l)-B(2) B( 3)-B(2)-B(5) 125.0 (14) 134.8 (11) B(3)-B(l)-H(l) B( 3)-B( 2)-H(2) 65.2 (1) 110.2 (8) B(4)-B(l)-H(5) B( 3)-B( 2)-H(5-2) 135.3 (13) 121.0 (2) B(4)-B(l)-H(l) B(5)-B(2)-Be( 1) 137.0 (14) 131.2 (11) B(5)-B(l)-H(l) B(5)-B(2)-H(2) 59.3 (1) 46.3 (10) B(l)-B(3)-B(2) B(5)-B( 2)-H(5-2) 56.6 (1) 96.4 (1 1) B( l)-B(3)-B(4) Be( 1)-B(2)-H(2) 123.7 (2) 90.3 (10) B(l)-B(3)-Be(l) Be( l)-B(2)-H(5-2) 131.8 (11) 111.0 (13) B(l)-B(3)-H(3) H(2)-B (2)-H(5-2) 99.2 (10) 51.0 (1) B(l)-B(3)-H(3-4) B(2)-B ( 1)-B ( 3) 91.1 (1) B(2)-B(l)-B(4) 97.4 (2) B(2)-B(3)-B(4) 64.8 (1) 65.3 (1) B(2)-B(3)-Be(l) B(2)-B( 1)-B(5) 138.0 (11) 126.4 (14) B(2)-B(3)-H(3) B(2)-B( l)-H( 1) 108.2 (9) 65.2 (1) B(2)-B(3)-H(3-4) B( 3)-B( 1)-B(4) 120.7 (2) 97.3 (2) B(4)-B(3)-Be(l) B(3)-B( 1)-B(5) 130.0 (11) 88.6 (1) B(4)-B(3)-H(3) B(3)-B(4)-B(5) 43.4 (10) 135.4 (11) B(4)-B(3)-H(3-4) B( 3)-B (4)-H( 4) 94.6 (11) 44.1 (9) Be( 1)-B( 3)-H( 3) B( 3)-B( 4)-H(3-4) 91.8 (10) 104.1 (9) Be(l)-B(3)-H(3-4) B( 3)-B(4)-H(4-5) 135.9 (1 1) H(3)-B(3)-H( 3-4) 108.6 (14) B(5)-B(4)-H(4) 58.2 (1) 106.7 (9) B(l)-B(4)-B(3) B( 5)-B(4)-H( 3-4) 51.0 (1) 45.9 (9) B(l)-B(4)-B(5) B(5)-B(4>-H(4-5) 137.1 (11) 108.3 (14) B(l)-B(4)-H(4) H(4)-B(4)-H(3-4) 101.4 (9) 109.5 (15) B(l)-B(4)-H(3-4) H(4)-B( 4)-H(4-5) 88.3 (13) B(l)-B(4bH(4-5) 101.5 (10) H(5-2)-B(4)-H(4-5) 58.3 (1) H(4-5)-B(5)-H(2-5) 90.2 (12) B( 1)-B(5)-B(2) 92.6 (14) 57.7 (1) B(3)-H(3-4)-B(4) B( l)-B(5)-B(4) 141.9 (16) B(4)-H(4-5)-B(5) 90.4 (14) B( 1)-B(5)-H(5) 100.0 (10) B(2)-H(5-2)-B(5) 89.5 (13) B( l)-B(5)-H(4-5) 101.8 (9) B( l)-B(5)-H(2-5)
the base of the square pyramid and of H ( l ) and (C5H5)Be toward one another is most likely due to electronic effects which have not yet been elucidated, as intermolecular distances are too great to cause packing distortions. The observed 4' tilt of the cyclopentadienyl hydrogens toward beryllium is consistent with the prediction of a calculation on C5H5BeH4 that the compactness of the Be orbitals would cause such a distortion in order to maximize overlap of CSH5orbitals with those on Be. (4) Jemmis, E. D.; Alexandratos, S.; Schleyer, P. v. R.; Streitwieser, A,; Schaefer, H. F. J. Am. Chem. SOC.1978, 100, 5695-5700.
Figure 1. Low-temperature structure of [p-(v5-CSHS)Be] B s H ~ .In this ORTEP drawing the nonhydrogen atoms are represented as 40% ellipsoids and the H atoms as 10% spheres. Table 111. Crystallographic Data for [p-(q5-C,H,)Be]B,H, mol wt 136.23 data collection temp, "C -100 radiation (graphite monochromator) Mo K O scan speed, deg/min 2-24 3-5 0 range of 2s, deg total reflctns 1800 total independent reflctns 1709 total obsd reflctns 1294 cryst system monoclinic h01, I odd; OkO, k odd systematic abs P2,lc (No. 14, second space group setting) equiv positions x, y , z;?, ' 1 2 + y , l / z f 2; x, 112 - y , ' 1 2 + z;K 7, no. of molecules/unit cell 4 d(calcd), g/cm3 0.978 lattice consts (errors) a, A 10.266 (4) b, A 5.616 (2) c, A 16.187 (4) P, deg 98.50 (30) v,A ) 923.0 (5) final discrepancy values 5.9 data to parameter ratio (aniso) 0.0551 R, 0.0831 R*
The thermal stability of [p-(~S-C5H,)Be]BSHs is surprisingly high. It decomposes slowly at 80 OC in C6D6and rapidly at 140 OC to uncharacterized insoluble materials. In di-n-butyl ether, however, there is no decomposition after several hours at 140 OC. It did not react with dimethyl or diethyl ether at ambient temperature nor with dimethyl ether at 100 OC in a benzene solution in sealed NMR tube experiments. No evidence of molecular rearrangement was obtained with these ethers. On the other hand, trimethylamine reacts rapidly, producing trimethylamine-borane as the only observable boron containing product. In contrast, 1,3-bis(dimethylamino)naphthalene did not react upon heating to 100 OC in C6D6 solution (or at ambient in diethyl ether), though it will deprotonate B5H9in C6D6 solution at 60 O c a s Reaction of [p-($-CSH5)Be]B,Hs with (CH3)*Zn in diethyl ether appears to result in deprotonation to form CH4 and what is tentatively characterized as [p12,~-(~S-CsH5)Be](p3,4CH3Zn)B5H7,whose l l B NMR spectrum contains five equally intense doublets at 6 -10.0, -12.4, -14.0, -17.8, -47.7. These shifts are wholly consistent with the formulation, as the [p($-C,H,)Be] gives rise to a large upfield shift to adjacent boron resonances, while the (p-CH3Zn) group causes a downfield shift of all boron atoms in the cage, vide infra. ( 5 ) Gaines, D.
F.;Jorgenson, M. W., unpublished results.
Structure
Inorganic Chemistry, Vol. 20, No. 7, 1981 2187
of [p-(s5-C5H5)Be]B5H8
Table IV. Final Atomic Positional Parameters and Isotropic Thermal Parameters ( A 2 ) for Ipu-(s5-C,H,)BelB,H, atom
104x 3530 (2) 2194 (2) 4074 (2) 3053 (3) 1897 (2) 2025 (2) 1479 (2) 3146 (2) 2993 (2) 1256 (2) 2662 (2) 1891 (21) 765 (19) 3942 (19) 3631 (18) 468 (25) 3565 (19) 2260 (20) 1103 (18) 3958 (19) 1519 (22) 5608 (24) 3143 (28) 1093 (27)
104~ 1704 (4) 1674 (4) 3827 (4) 5132 (4) 3800 (5) 6727 (4) 5710 (4) 6001 (4) 4406 (4) 4114 (4) 4383 (4) 8329 (44) 6606 (35) 6934 (35) 3928 (36) 3217 (50) 4058 (36) 2700 (39) 3627 (36) 560 (38) 632 (44) 4146 (42) 6709 (58) 4276 (5 1)
1042 3684 (1) 3747 (1) 4029 (1) 4299 (1) 4128 (1) 1260 (1) 2135 (1) 2107 (1) 1118 (1) 1151 (1) 3159 (1) 1022 (15) 2475 (14) 2426 (13) 705 (13) 775 (18) 1846 (14) 1215 (12) 1922 (13) 3406 (14) 3544 (16) 3996 (16) 4561 (21) 4216 (19)
Bise
Experimental Section
4.6 (5) 3.6 (5) 3.4 (4) 3.1 (4) 6.3 (7) 3.5 (5) 3.7 (5) 3.3 (4) 3.4 (5) 4.6 (6) 5.0 (6) 7.3 (8) 6.5 (7)
Table V. Anisotropic Thermal Parametersa (X lo3) for Iw-(.rl'-C,H,)BelB,H. atom C(1) C(2) C(5) C(4) C(3) B(1) B(2) B(3) B(4) B(5) Be(1)
U,, 38(1) 39(1) 38(1) 93(2) 51(1) 58(2) 35 (1) 40(1) 37(1) 32(1) 32 (1)
u 1 2
u33
u 1 2
39 (1) 45 (1) 51 (1) 38(1) 72(2) 31(1) 39 (1) 37 (1) 42(1) 43(1) 38 (1)
38(1) 42(1) 36(1) 23(1) 38(1) 29(1) 28 (1) 28(1) 31 (1) 31 (1) 25 (1)
8(1) -5 (1) -7(1) 7 (1) 25 (1) -1(1) 6 (1) -11 (1) -8 (1) -1 (1) O(1)
a Of the form e ~ p [ - 2 n ' ( U , , h ~ a *+~U22k2b*2 2U,,hka*b* t 2U,,hla*c* + U,,klb*c*)].
The reaction of (CH,)2Zn with the title compound in C6D6 solution is very different. First, the reaction is very slow, requiring more than 1 month to reach completion in the dark. The reaction is much faster in the presence of light but is then complicated by a side reaction that produces significant quantities of a metal, presumably zinc. Second, the IlB NMR spectrum of the product contains three doublets in 2:2:1 ratio at 6 -9.1, -19.3, and -48.5, respectively. A mass spectrum was not obtained owing t o the low volatility of the product, but t h e formation of ($-C5H5)BeCH3 in the reaction leads us to postulate that, in the absence of a basic solvent, the reaction produces (p-CH3Zn)B5HEaccording to eq 3. A (CH3)2Zn
+
-. +
[P-(V5-C5H5)Be1B5H8 (q5-C5H5)BeCH3 (p-CH3Zn)B5H8 (3)
similar compound, p,p'-Hg-(B5HE),, having a similar * l B NMR spectrum has recently been reported.6 Other synthetic routes to the largely unstudied zinc-borane clusters are under investigation. B r ~ n s t e dacids react rapidly and cleanly with the title compound in nonbasic solvents to produce B5H9according to eq 4. [p-(q5-C5H5)Be]B5H8 HX ($-C5HS)BeX B5H9 X = C1, Br, OH (4)
+
-
In aromatic solvents such a s C6D6, insoluble orange-brown solids form, suggesting the formation of solvated salts such as (C5H5)Be(C6D6)+X-, which have been described elsehere.'^ Upon standing for 1 week, B5H9had undergone exchange with the C6D6 to form 1-DB5H8,presumably catalyzed by a beryllium complex ( 1-DB5HEhas been prepared from B5H9and C6D6 in the presence of A1C137b).
+
(6) Hosmane, N. S.; Grimes, R. N. Inorg. Chem. 1979, 18, 2886-2891.
All manipulations of beryllium-containing materials were performed in a glovebag in a fume hood or in a glass high-vacuum system.* Beryllium chloride was vacuum sublimed before use. Methylene chloride was distilled from 3-1%molecular sieves, and other solvents were distilled from LiAlH4. All the beryllium- and boron-containing materials discussed are expected to be air- and moisture-sensitive, toxic, and in some cases pyrophoric. The NMR spectra were obtained with a Bruker WH-270 ('H at 270 MHz, IlB at 86.7 MHz9) spectrometer. Samples were contained in sealed 5-mm 0.d. NMR tubes. Infrared spectra were obtained on a Perkin-Elmer 700 spectrophotometer. Routine samples were obtained in the gas phase in a 10-cm cell with NaCl windows. Spectra for samples of very low vapor pressure were obtained by condensing the sample as a film on a polycrystalline ZnS window cooled to -196 OC which was mounted inside a vacuum IR cell having NaCl windows. Mass spectra were obtained on an AEI MS-902 spectrometer. Samples were introduced directly as a vapor from a vacuum flask equipped with O-ring stopcocks. Preparation of [p-($-CSHS)Be]B5H8. The reaction of a stirred pentane slurry of 10 mmol of KB5H8Iowith excess CSHSBeC1,"while the reaction mixture was warmed from -40 OC to ambient, produced high yields of [p-($-C5Hs)Be]BsH8, which was purified by highvacuum trapto-trap fractionation. The compound is a colorless solid of low volatility (vp 3 4 0 . The structure consists of discrete molecules with a squareplanar arrangement of the carbon ligands. The platinum-methyl bond distance (2.068 (8) A) is significantly shorter than the platinum-Cp distance (2.151 (8) A). The platinum-olefin distance trans to the Cp ligand is shorter than the one trans to the methyl group. These facts are consistent with the previous observation that the NMR trans influence of the Cp ligand is much smaller than that of the methyl group. The differences in the bonding of the two sp3-hybridized carbons are discussed in terms of u-T hyperconjugation of the Pt-Cp bond with the diene.
1,
Introduction Recently the title compound (1) was prepared and some of its reactions reportede2 This complex undergoes a Diels-Alder addition of hexafluoro-2-butyne in which the acetylene adds to the Cp ring (Cp = C5H5) trans to the platinum atom ~ubstituent.~This was taken to imply that the metal does not take part in the mechanism of the addition other than possibly acting as a bulky steric hindrance to the approach on one side of the Cp ring. This is in contrast to "metal-assisted" cycloaddition reactions observed in some iron' and nickel5 systems. It was of interest, therefore, to determine the structure of 1 to establish if there was any unusual steric feature that might prevent precoordination of an acetylene. Also of interest was the comparison of the F't-CH3 and R-($-Cp) bond distances. A priori, they would be predicted to be very similar since both are single bonds to sp3 carbon, atoms. However, the Mo-CH3 bond distance in ($CP)~MO(NO)CH~ is about 0.1 A shorter than the Mo-($-Cp) bond distance in Cp3Mo(N0).6 The title complex is an ideal (1) (a) University of Nebraska. (b) Department of Chemistry, McGill University, 801 Sherbrooke St. W.,Montreal, Quebec, Canada H3A 2K6. (c) University of Guelph, Guelph, Ontario, Canada N l G 2W1. (2) H.C. Clark and A. Shaver, Can. J. Chem., 54, 2068 (1976). (3) H.C. Clark, D. G. Ibbott, N. C. Payne, and A. Shaver, J . Am. Chem. Soc., 97,3555 (1975). (4) R. E. Davis, T. A. Dodds, T.-H. Hseu, J. C. Wagnong, T. Devon, J. Tancrede, J. S. McKennis, and R. Pettit, J . Am. Chem. Soc., 96,7562 (1974). (5) D. W.McBride, E.Dukek, and F. G. A. Stone, J. Chem. Soc., 1752 (1964).
0020-1669/81/1320-2188$01.25/0
model to investigate the generality of such differences since both types of ligands, CH3 and ~ l - C pare , in the same complex, and they are situated trans to identical olefin ligands. There is spectroscopic evidence that a significant difference in the bonding of the methyl and Cp groups exists in 1. NMR coupling constants are often used to estimate the relative trans influences of different groups in platinum complexes.' Comparison of the J(Pt-C) and J(Pt-H) values for the COD group (COD = 1,5-cyclooctadiene) trans to the methyl and Cp ligands indicated that the N M R trans influence of the latter was much less than that of the methyl group.2 This seems inconsistent with both groups being bound to the platinum atom by identical metal-carbon (sp3) bonds, particularly, since other N M R studies have shown there is little or no discrimination among sp3-hybridized carbon ligands.* Experimental Section Large, well-shaped, yellow single crystals of 1 suitable for X-ray studies were grown from diethyl ether at -20 "C. Weissenberg and precession photographs were used to determine the probable space group and a preliminary set of lattice constants indicated monoclinic, 2/m, symmetry. The systematically absent reflections were those uniquely required by the centrosymmetric s p c e group, n l / n (a special (6) F.A. Cotton and G. A. Rusholme, J. Am. Chem. Soc., 94,402(1972).
(7) T. G.Appleton, H. C. Clark, and L. E. Manzer, Coord. Chem. Rev.,
10, 335 (1973). (8) (a) M. R. Collier, C. Eaborn, B. Jovanovic, M. F. Lappert, Lj. Mane jlovic-Muir, K. W.Muir, and M. M. Trudlock, J. Chem. Sw.,Chem. Commun., 613 (1972). (b) C. J. Cardin, D. J. Cardin, M. F. Lappert, and K. W.Muir, J . Chem. Soc., Dalton Trans., 46 (1978).
0 1981 American Chemical Society
